This application relates to a damping circuit associated with a motor drive for a motor to be powered by a DC power bus.
Many electrical systems include a power bus that passes electric power among a number of components associated with the system. One example is an aircraft electrical power system. In such a system, a DC power bus supplies power to many components mounted around the aircraft.
Such systems typically include electric generators which are driven by prime movers, such as gas turbine engines, to generate AC power. A gear box is typically included between the prime mover and the generator. The AC power is converted to DC and passed to the power bus.
There are a number of torsional and vibratory challenges in such systems. Mechanical dampening systems have been incorporated, however these are complex and require a good deal of space and weight.
More recently, generator control units have been provided with damping algorithms that modulate the DC bus voltage. The bus voltage modulation, in combination with a resistive load on the bus, is used as a means of damping mechanical oscillations in the prime mover/generator system.
However, when the bus loading is not resistive, these damping algorithms are ineffective. Such is the case when a motor drive with a constant power algorithm is connected to the bus. The constant power algorithm in the motor drive makes it appear as a negative impedance load on the bus.